The invention relates to a method and a device for controlling an electrically actuated wear adjusting device of a brake application system for vehicles, particularly rail vehicles.
European Patent Document EP 0 699 846 A2 describes a brake application system for rail vehicles, having a caliper-type brake linkage for a disc brake which has, as the screw drive between two brake linkage parts, a mechanically actuated wear adjuster constructed as a thrust rod actuator or as a brake rod actuator. The wear adjuster keeps the brake pad play constant in the event of a wearing of the pad or the brake disc. This takes place by a change of length of the screw drive, in the case of thrust rod actuators, an increasing actuator length causing a reduction of the brake pad play. The drive of the known screw drive takes place mechanically by a brake linkage with a thrust rod which, in the event of an excess stroke of a brake actuator constructed as a pneumatic cylinder—piston driving gear, is operated by a rocker lever. An emergency release of the brake, that is, an emergency-caused braking force reduction of the brake being affected by braking force, takes place by the pneumatic brake actuator. For the auxiliary release of the brake not affected by braking force for maintenance work, for example, for changing the brake pads, the threaded spindle is rotated manually.
The present method and system in one embodiment measured values for the application path, and the assigned braking force values are used as the starting basis for the calculation of the actual application stroke and of the adjusting path that may be required.
The method according to another embodiment is based on a predetermined desired application point in which the brake pad play should be equal to zero. This desired application point is approached and then the wear adjuster, if necessary, is actuated until a measured electric braking force signal is present for the first time and the actual application point has been reached. The covered path between the desired application point and the actual application point of the brake pads will then correspond to the adjusting path. The subsequent restoring of the brake application system into the release position therefore starts out from the actual application point, so that the brake pad play caused by wear will no longer exist for future application movements.
The wear adjuster of all of the embodiments, instead of being mechanically actuated, is electrically actuated. Thus, the known mechanical large-size actuating mechanism is eliminated, which results in a smaller size. In addition, a more precise adjusting of the brake pad play than previously can be achieved. This increases the dynamics of the brake application system.
In the first embodiment, the covered application path of the brake pads during the service braking is directly or indirectly measured on a moved component of the brake application system.
During a service braking taking place with a higher braking force, the brake force value and the respectively assigned covered application path of the brake pads may be measured several times successively. By means of the supporting points obtained therefrom, an essentially linear braking force—application path course can be shown, from which the actual application stroke is mathematically extrapolated. Braking at a higher braking force in this case is a braking during which braking force values of approximately more than 3% to 20% of a maximally possible braking force value occur.
In contrast, during a service braking which took place at a lower braking force, only the braking force value occurring once and the assigned covered application path of the brake pads are used for determining the actual application stroke. Braking at a lower braking force is a braking during which braking force values of approximately less than or equal to 3% to 20% of a maximally possible braking force value occur. At lower braking force values, this method is more precise because no strictly linear braking force—application path relationship is yet present from which the application point could be extrapolated.
The adjusting of the brake pad play may take place in the not-applied condition of the brake application system. A relatively low and cost-effective drive of the wear adjuster will then be sufficient for generating only the braking force required for producing a measurable braking force signal.
The second embodiment is implemented at least during the upgrading or initializing from a emergency-released or auxiliary release position of the brake application system together with a test run.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.